1. Field of the Invention
The present invention is generally directed to an air quality control system (AQCS) useful for processing a gas stream, such as a flue gas stream emitted from a fossil fuel fired boiler, a combustion process or the like. More particularly, the present invention is directed to an integrated fabric filter module and dry scrubber system for an AQCS with increased “turn down” capabilities useful for processing a gas stream.
2. Description of the Related Art
In the treatment of flue gases or gas streams, fabric filters and dry scrubber systems are known. For example, U.S. Pat. No. 7,189,074 invented by Ching Chiu Leung et al., describes a method and process for co-combustion in a waste to energy cement production facility. The described co-combustion process involves:                1. Cement Process System;        2. Waste Reception/Handling System;        3. Waste Co-combustion System;        4. Dry Scrubbing System;        5. Power Generation System;        6. Secondary Scrubbing System; and        7. Flue Gas and Ash Treatment System.Hence, the process utilizes two scrubbing systems, the second of which includes a baghouse filtration step, i.e., passing flue gasses through bag fabric filters to collect dust/ash. It may be noted that the co-combustion process described above requires a number of systems, each of which being indicative of significant capital, maintenance and operating expenses.        
Likewise, U.S. Pat. No. 7,141,091 invented by Ramsay Chang describes a method and apparatus for removing particulate and vapor phase contaminants from a gas stream. The method removes particulate and vapor phase contaminants from a gas stream by using a scrubber configured to remove an absorbable form of the vapor phase contaminant, wherein the scrubber is located downstream of and is fluidly connected to the particulate collection device. The particulate collection device may include one or more electrostatic precipitators and one or more baghouse filtration systems. It may be noted that the particulate and vapor phase contaminants removal method as described above requires a number of systems, each of which being indicative of significant capital, maintenance and operating expenses.
While there exist methods and equipment capable of removing both particulate and vapor phase contaminants from a gas stream, there remains a need for an improved method and equipment that enables increased “turn down” when in operation to reduce operation associated costs and to improve efficiency and effectiveness.